Durable ceramic decorating enamels based on thermally stable cadmium red colors

Abstract

Ceramic articles are provided with cadmium red-based decorations of improved chemical durability, by firing the decorations onto the articles at high temperatures. The cadium red-based enamels used for decoration are protected against color burn-out during high-temperature firing by a color stabilizing agent consisting of a fritted, sinterable, devitrification resistant alkali borosilicate glass which is combined with the enamels prior to firing.

We claim: 
     
       1. In a decorating enamel suitable for providing a fired decoration on a ceramic article consisting of, in combination, a cadmium red pigment consisting essentially of CdS/CdSe; and   an enamel flux consisting essentially of a CdO--PbO--B 2  O 3  --SiO 2  glass;   the improvement comprising the addition to the enamel of a color stabilizing agent consisting of a sinterable devitrification-resistant alkali borosilicate glass in glass frit form.   
     
     
       2. A decorating enamel in accordance with claim 1 wherein the color stabilizing agent is provided as a discrete layer of glass frit covering the pigment and enamel flux. 
     
     
       3. A decorating enamel in accordance with claim 1 wherein the color stabilizing agent is dispersed as a glass frit throughout the combined pigment and enamel flux. 
     
     
       4. A method of improving the stability of a CdS/CdSe-based ceramic decorating enamel against color burn-out during firing, said decorating enamel consisting of a cadmium red pigment consisting essentially of CdS/CdSe and an enamel flux consisting essentially of a CdO--PbO--B 2  O 3  --SiO 2  glass, which method comprises the step of combining the enamel prior to firing with a color stabilizing agent consisting of sinterable, devitrification resistant alkali borosilicate glass in glass frit form. 
     
     
       5. A method in accordance with claim 4 wherein the color stabilizing agent is provided as a discrete layer of glass frit covering the enamel. 
     
     
       6. A method in accordance with claim 4 wherein the color stabilizing agent is dispersed as a glass frit within the enamel.